The drive toward higher integration densities of electronic devices has led to smaller transmission line conductor sizes and compound dielectric structures with multiple lossy dielectrics. The desire for higher bit-rates, upwards of 100 GBits/s, has led to increased skin-effects, proximity effects, and dielectric losses. Losses in these transmission lines are often difficult to predict due to non-ideal transmission line cross-sections, including surface roughness, edge-shape effects, and moisturThe drive toward higher integration densities of electronic devices has led to smaller transmission line conductor sizes and compound dielectric structures with multiple lossy dielectrics. The desire for higher bit-rates, upwards of 100 GBits/s, has led to increased skin-effects, proximity effects, and dielectric losses. Losses in these transmission lines are often difficult to predict due to non-ideal transmission line cross-sections, including surface roughness, edge-shape effects, and moisture absorption in organic dielectric materials. Therefore, in this work, a methodology for modeling the conductor in transmission lines is proposed that includes the edge-shape effects and surface roughness over a wide frequency range. First, it is shown that state-of-the-art models are deficient due to limitations in their bandwidths, flexibility, and computation times. A novel model, which models the direct current (DC) resistance, skin-effect, and proximity effect together with the edge-effects and surface roughness effects, is proposed called the Adapted Filament Method. By modeling these effects together, it is possible to model extremely non-ideal transmission lines (for example, lines produces with ink-jet printing processes) where the surface roughness is a significant proportion of the conductor thickness, edge-shape effects include very narrow angles, and each conductor surface has a different roughness profile. The proposed model extends the filament method by building an inhomogeneous conductivity toward the conductor surfaces. The Adapted Filament Model offers more accurate results than the state-of-the-art models over a larger frequency bandwidth with greater physical insight. It also models proximity effects together with surface roughness effects, which is a deficiency of nearly every other model. Due to its physical insight the model is also useful for evaluation of transmission line fabrication technologies because it can determine dominant loss mechanisms in given frequency ranges. Furthermore, state-of-the-art techniques are investigated for modeling the dielectric losses in structures where several dielectric layers, with various characteristics, contribute to the losses. The most important composite dielectric modeling techniques were investigated to determine composite material dielectric loss characteristics. Based on these, a combination of modeling techniques is developed to analytically model a complex dielectric structure, including the effects of moisture absorption. The methodology was used to investigate, analytically, for the first time, the effects of moisture absorption on the high frequency characteristics of coplanar transmission lines. This investigation showed an increase in dielectric losses and permittivity dispersion at low frequencies. The conductor modeling approached were verified with high frequency measurements of coplanar transmission lines. The lines were fabricated with the before mentioned innovative ink-jet micro-printing process. The modeled results correspond to the measured results within a few percent. Three different transmission lines with different dimensions and metallization conductivities were measured and modeled up to 60 GHz. Modeling shows that, for a coplanar transmission line printed with an ink-jet printing technique, edge shape effects and surface roughness became the dominant loss mechanisms at around 5 GHz and accounted for 70% of the total losses at 20 GHz. When lower conductivity ink was used (approximately 1/5 of the previous), while the skin- and proximity effect losses increased, the surface roughness and edge-shape effects only accounted for 20% of the losses at 60GHz. The composite dielectric modeling techniques were verified for a lossy dielectric encapsulation material using planar interdigital capacitors up to frequencies of 110 MHz. It is shown that the effective permittivity and dielectric loss tangent of a composite dielectric are frequency dependent at low frequencies, but this dependency stabilizes at around 200MHz. Finally, the dielectric and conductor modeling techniques were applied together to find the broadband transmission line characteristics of a coplanar transmission line. For a typical application, the combined modeling indicates low frequency dielectric losses and characteristic impedance dispersion that stabilizes around 1 GHz.…